From Steve Schweitzer's A Fly Fishing Guide To Rocky Mountain National Park, flyfishingrmnp.com:
Summerland Park Area
Only minutes into the hike long the scenic North Inlet Trail, you'll approach a smooth stretch of North Inlet Creek. The stream is 20-23 feet wide and appears slow flowing due to the smooth surface apearance, although the flow is ...
US-34 to W Portal Rd to Tonahutu/North Inlet Trailheads. North Inlet Trail is a gem of a trail and fishery from the very start. After a short three-quarter mile hike from the trailhead, the river meets the trail on the right. It's all one can do to not stop and fish the gorgeous flat stream water. For the next mile and a quarter, the trail heads to the north while the stream flows a few hundred yards to the south. This is Summerland Park. For the first three miles fro the trailhead, the trail is relatively flat, gaining only a few hundred feet of altitude as it closely follows North Inlet Creek to Cascade Falls. For the next 2.8miles to the junction of Ptarmigan Creek (Bench Lake outlet) give you plenty of streamside fishing opportunity. The next mile take you to the junction of Lake Nanita Trail. From here, the trail gets decisively steeper and veers north of any fishing water.